Phage recombinases are splicing enzymes used by virions to insert or remove their genomic DNA from a host chromosome. The use of recombinases (or integrases) for genomic manipulation is well established. Site-specific recombinases are significant tools in a variety of applications in research, medicine, and biotechnology. Conditional gene targeting using site-specific recombinases has enabled the functional analysis of genes, which cannot be inactivated in the germline. Site-specific recombinases also allow the precise integration of open reading frames (ORFs) encoding proteins of interest into highly active gene loci in cell lines and transgenic animals. Recombinases are disclosed in the following references: Groth, Amy C.; Calos, Michele P. J. Mol. Biol (2004) 335, 667-678; Silver, Daniel P.; Livingston, David M. Molecular Cell (2001), 8, 233-243; Sauer, Brian; McDermott, Jeffrey. Nucleic Acids Research (2004) 32(20), 6086-6095; Yagil, Ezra; Dorgai, László; Weisberg, Robert A. J. Mol. Biol (1995) 252, 163-177; and, Dorgai, László; Yagil, Ezra; Weisberg, Robert A. J. Mol. Biol (1995) 252, 178-188.